Singapore's internet regulator will block access to infidelity website AshleyMadison.com following a public uproar over the Canada-based site's plan to offer a service in the Southeast Asian city-state.

Scrutiny of the site, which claims 22 million members in about 30 countries, forms part of a wider debate over censorship in the country of 5.4 million people.

"We recognize that site blocking is not a perfect way of denying access to prohibited content, as it can be circumvented," Singapore's Media Development Authority (MDA) said in a statement late on Friday.

"The Ashley Madison website, however, stands out. It aggressively promotes and facilitates extramarital affairs and has declared that it will specifically target Singaporeans."

Tens of thousands of Singaporeans signed petitions urging the government to block access to Ashley Madison and Minister for Social and Family Development Chan Chun Sing wrote on his Facebook page that he did not welcome the site to Singapore.

AshleyMadison.com, founded in Canada in 2001, is an online dating and social networking service marketed to people who are already in a relationship.

It started a Japanese service in June and a Hong Kong service in September, and its operator had planned to launch in Singapore on November 17.

But some Singaporeans say banning such a website would serve no purpose other than giving the operator free publicity.

"What is to stop alternative websites from taking the place of Ashley Madison? ... If technology and human nature were to reduce such a ban to a paper tiger, then it would not protect public morality," said a letter to a newspaper forum.

Singapore bans Playboy magazine and blocks dozens of websites in what it has described as "a symbolic statement of the types of content which the community is opposed to".

- Reuters